The genus Onosma belongs to the Boraginaceae family and contains over 230 species. The present review sheds light on the ethnopharmacology, phytoconstituents, bioactivity, and toxicology of the Onosma species from previous investigations. Furthermore, the paper also highlights the unresolved issues for the future investigations. The review included previous studies of the genus Onosma available from Google Scholar and Baidu Scholar, Science Direct, SciFinder, Wiley Online Library, and Web of Science. Until now, more than 200 chemical compounds have been detected from the genus Onosma, including naphthoquinone (33), flavonoids (30), hydrocarbon (23), phenolic (22), ester (17), alkaloids (20), aromatics (12), carboxylic acid (11), fatty acids (9), terpenoids (10), while the most important ones are rosmarinic, ferulic, protocatechuic, chlorogenic, caffeic, p-coumaric acids, and apigenin. The Onosma species are reported as traditional medicine for wound healing, heart disease, and kidney disorders, while the pharmacological investigations revealed that the extracts and the phytochemicals of Onosma species have different therapeutic properties including antioxidant, enzyme inhibitory, antitumor, hepatoprotective, antiviral, anti-inflammatory, and antimicrobial actions. The summarized knowledge in this review provides valuable ideas for the current and future drug discovery and a motivation for further investigation on the genus Onosma.

An easily performed, specific, sensitive, rapid, reliable and inexpensive procedure for the spectrofluorometric quantitation of ascorbic acid was proposed using acriflavine as a fluorescence quenching reagent. The procedure was based on the determined quenching effect of ascorbic acid on the natural fluorescence signal of acriflavine and the reaction between ascorbic acid and acriflavine in Britton-Robinson buffer solution (pH 6) to produce an ion-associated complex. The reduction in acriflavine fluorescence intensity was detected at 505 nm, while excitation occurred at 265 nm. The relationship between quenching fluorescence intensity (ΔF) and concentration of ascorbic acid was linear (R 2 = 0.9967) within the range 2-10 μg/ml and with a detection limit of 0.08 μg/ml. No significant interference was detected from other materials often found in pharmaceutical nutritional tablets. The obtained results were compared with those from high-performance liquid chromatography and appeared in good agreement, with no important differences in precision or accuracy. The proposed spectrofluorimetric method was used to determine the amount of ascorbic acid in a number of commercial pharmaceutical nutritional supplement tablets with a 95% confidence performance.

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A new fluorescent probe L-Tryptophan was reported for the determination of folic acid (FA), based on its quenching effect of the fluorescence intensity of L-Tryptophan. The concentration of folic acid was proportional to the quenched fluorescence intensity of L-Tryptophan at an emission wavelength of 365 nm in Britton– Robinson (BR) buffer solution of pH 7. Optimized conditions of pH, time, order of addition of the reagent, potential interferences, concentrations of L-Tryptophan and buffer were investigated. Folic acid was determined in a linear range of 2.0 to 16.0 μg ml-1 with a correlation coefficient R2 0.9974. The limits of detection LOD and quantification LOQ values were 0.09 μg ml-1 and 0.27 μg ml-1, respectively. The standard deviation (RSD) values for five replicated measurements of 2, 8, 16 μg ml-1 folic acid were between 0.23 % and 1.07%. This method is efficient for routine analysis and quality control assay as it is relatively interferences free.

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